Willamette Bridge Railway, incorporated in 1887, was a narrow gauge system that connected east and west sides of Portland across the Steele Bridge built in 1888 (Wikipedia) over the Willamette River. It was the first electric line in Portland, initially operating horse-drawn streetcars (Wikipedia). The W.B. Ry. Co. system was merged with the Transcontinental system to form the City & Suburban Railway Company in 1891 (RailsWest.com).
W.B. Ry. Co. also used steam power (The Oregon Historical Society) before its electric rail network was completed. See operators of the electric trolley car No. 20 in Nov. 1889 below, wearing the uniform featuring buttons.